It is known that α,β-diaminopropionic acid derivatives can be prepared by Rh-catalyzed asymmetric hydrogenation according to Scheme 1 (J Org Chem, Vol. 66, 11, 2001, pages 4141-4147). However, the asymmetric hydrogenation succeeds only when both nitrogen atoms have been acylated.

The attempt to hydrogenate N,N-dimethyleneamines or N,N-dimethylene-enamines was without success.